The subject matter disclosed herein relates to enhanced engine load demand anticipation and, more particularly, to using angle of attack data in enhanced engine load demand anticipation in a helicopter.
In a rotary-wing aircraft application, engine anticipation may be part of the engine control system to maintain rotor speed within a relatively narrow range in response to demanded torque from the rotary-wing aircraft rotor system. The capability of the engine control algorithm to correctly anticipate changes in power required directly impact rotor speed governor performance.
Conventional engine power anticipation algorithms include collective pitch based anticipators, predictive anticipators and lookup-table based anticipation algorithms that add atmospheric variation, reference rotor speed and airspeed data to collective anticipation concepts. In some cases, tail rotor power requirement data is also added.
Collective pitch based anticipators are most commonly utilized on current generation rotary-wing aircraft. The engine power anticipation algorithm utilizes changes in collective control displacement as collective pitch change has a significant effect on power required. The collective control position is monitored and fuel flow is adjusted based on collective control displacement. This type of an algorithm is typically implemented via mechanical or electronic feedback. Collective pitch based anticipator performance may be imperfect, however, since power required depends on a multitude of factors, such as air speed, gross weight, maneuver, etc.
Predictive anticipators are currently under development. This category of engine power anticipation algorithms monitor various states of the aircraft and attempt to predict changes in power required with a neural-network which must be trained on each particular engine and aircraft. There are known certification issues with predictive anticipators, however, since the neural network is not deterministic.